Field of the Application
The present application relates to a control device for an internal combustion engine, and more particularly relates to a control device for an internal combustion engine including a turbocharger.
Background Art
Conventionally, Japanese Patent Laid-Open No. 2013-096372, for example, discloses a device which detects an abnormal state (a stuck state) of an air bypass valve (ABV) and a wastegate valve (WGV), in an internal combustion engine including the ABV which is provided in the passage bypassing the compressor of a turbocharger, and the WGV which is provided in the passage bypassing the turbine of the turbocharger. The device issues a command to open the ABV when the engine operation state enters a predetermined surge region, and detects that the ABV is stuck closed based on the time period required until the engine operation state gets out of the predetermined surge region, after the issuance of the command.
Further, the device determines whether the ABV is stuck open or the WGV is stuck open by comparing the estimated value of the turbocharging pressure which is calculated in advance in a specific engine operation state where the WGR is opened, with the actual measured value of a pressure in the passage provided with the ABV in the specific engine operation state. More specifically, the device determines that the ABV is stuck open when the actual measured value is smaller than the estimated value, and determines that the WGV is stuck open when the actual measured value is larger than the estimated value. In this way, according to the device in Japanese Patent Laid-Open No. 2013-096372, sticking open and sticking closed of the ABV, and sticking open of the WGV can be determined.
Further, National Publication of International Patent Application No. 11-509908 discloses a device which detects an abnormality of an exhaust system in an internal combustion engine which includes two intake manifolds, two exhaust manifolds, two intake passages, two exhaust passages, two turbochargers, two ABVs and two WGVs corresponding to two cylinder banks, and a common intake passage between the two intake manifolds and the two intake passages. More specifically, the device compares the exhaust pressures or the exhaust gas flow rates in the respective exhaust manifolds. When the exhaust pressure difference or the exhaust flow rate difference exceeds a threshold value, the device estimates that either one of the exhaust systems has a fault.
Other prior arts include Japanese Patent Laid-Open No. 2010-106787, Japanese Patent Laid-Open No. 2005-344707, Japanese Patent Laid-Open No. 2005-207398, Japanese Patent Laid-Open No. 2006-322335, Japanese Patent Laid-Open No. 2012-188994, Japanese Patent Laid-Open No. 2012-180822, and Japanese Utility Model Laid-Open No. 62-76252.
An internal combustion engine having a configuration as in National Publication of International Patent Application No. 11-509908 includes two ABVs and two WGVs, and therefore, it is desirable to be able to detect which one of the ABVs and the WGVs, the number of which are four in total, has an abnormality accurately. However, the device disclosed in Japanese Patent Laid-Open No. 2013-096372 is not premised on the internal combustion engine with the configuration as disclosed in National Publication of International Patent Application No. 11-509908. Further, the device in National Publication of International Patent Application No. 11-509908 can only estimate that either one of the exhaust systems has a fault, and cannot determine which one of the ABVs and the WGVs has an abnormality.